Rock drill



J. c. cuRfrls ROCK DRILL ,May 11, 1943.

Filed May 5l, 1940 IIIIIIIIA .IIJIMIUHMIAINWW a A [2206222021: zzz 5 @212219. 5M 4MM.

Patented May 11, 1943 noon Daim.

John C. Curtis, Claremont, N. H., assigner to Sullivan Machinery Company, a corporation of Massachusetts Application Mayv 31, i940, serial No. 338,026

13 Claims.

This invention relates to rock drills, and more particularly, but not exclusively, to improvements in the automatic feeding means forhammer rock drills of the mounted, shell guided type.

In hammer rock drills of the mounted, ,shell guided type,.the vibrations set up ,within the hammer motor during operation thereof are frequently employed to effect feed of the hammer motor with respect to the guide shell toward and from work, and means is-usually associated with the hammer motor for controlling the direction of feeding movement of the hammer motor along the guide shell. Such vibration operated feeding means are known as automatic jump feeds and a exible control element, such as a control chain, is sometimes associated with the hammer motor in the feeding thereof. 'Ihe control chain is attached to the motor andpasses around guide rolls spaced longitudinally of the drill near the opposite extremities of the guide shell and there is obtained the most effective feed when the control chain isheld underI a given tension. Since there is substantially no resilience inthe control chai-n employed -there will be, in the absence of yielding tensioning means, a large decrease in the tension of the chain and a corresponding reduction in the effectiveness of feed if the chain connections are moved but a slight amount sufficient to loosen the chain. A loosening of the control chain willfnot only result in a large reduction in the rate of drill feed, but also will result in a whipping about of the chain which increasesl the wear on the chain and its associated parts. Also in-such feeding means when the control chain is held under suflicient tension to effect drill feed i" most eiectivelf/,yitwis practically impossible manually to f eed the hammer motor along the shell guideway due to the tight engagement of the control chai-n with its guide rolls and. it is therefore necessary to effect loosening` of the chainvwhen it is desired to effect manual movement of the hammer motor. A

.It is thereforev `an, object of this invention to provide improved means for maintaining the nexible control element of an automatic vibration# controlled rock drill feed under a given tension during the drillingoperation. Another object is to provide improved automatic tensioning means for the flexible control element and havingjasseciated therewith means for automatically substantially reducing or relieving the tension thereon when drilling is discontinued. Another'object is to provide improved means for yieldingly contor and automatically maintaining a predetermined tension on the controlchain. A further object is to provide an improved automatic chain tensioning means of the fluid operated type. Still another object is to provide .improved vmeans ,for holding the control chain for. a rock drill o f the hammer type at a given tension when the drill motor is. no-t running .and having associated therewith means for increasing the tension onthe control chain when the hammer motor is running. Otherl objects and ladvantages of the .invention will, however, hereinafter `more fully appear'. I

In the accompanyingdrawing Vthere are shown for purpose of illustration two forms and a modiiication which the invention may assume in practice. Y

In this drawing: A Fig. 1 is a view in longitudinal vertical section, with parts in elevation, illustrating a rock drill with which an illustrative embodiment of the improved chain tensioning means is associated.` 1

Fig. 2 is a longitudinally extendingvhorizontal sectional view taken substantially on the'line 2 2 of Fig. 1.r Fig. 3 is an enlarged cross-sectional view taken substantially on the line 3 3 of Fig. 1. v Fig. 4 is an enlarged ver-tical sectional view taken substantially on the pla-ne of the line 4 4 ofFig.2. n 1 q Fig. 5 is a detail sectional view thro-ugh a modi- A lied form of control means for the chain tensione ing lmeans shown in Fig. 4. l

HFig. 6 -is Aa horizontal sectional View through another modied form 0f chain tensioning means;V In the illustrative embodiment of theinvention shown in Figs. `1- to 4, inclusive, -a' guidershel-l'flv slidably supports a drilling motor generally 'desigs n ated 1 2 4of the pressureffluid actuated-:hammer type.v The drilling motor comprises a cylinder 3 *u having a-bore 4.containing a reciprocatory har'n mer piston- 5. v 'Ihe hammer piston has 'a striking hart guided -in the'front cylinder head1 fordeliveri-ng-impact blows to the shank of a drill steel 8', vthelatter being suitably supported in a usual chuck mounted within a front chuck housing 9.'

` necting the control chain to thedrill hammer ino- A throttle valve It arranged in a rear head block Il is vprovided with an operatingvhandle l2. for. adjusting the valve to control the supply of pres-f sure fluid from a supply connectionlB to any suitable fluid distributing valve means (not shown) which controls the supply of fluid pres#y sure to the cylinder bore. The cylinder 3, front chuck housing 9 and rear head block I I are held in assembled relation by means of usual side rods i4. The guide shell l is provided with longitudinal guideways I5, as shown in Fig. 3, for slid;

ingly receiving lateral guides I6 formed along the sides of the motor cylinder 3, and is provided with a bottom trunnion support I'I adapted to be clamped in a suitable saddle mounting of a suitable support.

The automatic vibration co-ntrolled, feed-effecting-means herein comprises a control chain I8 arranged Within the guide shell in planes parallel with the guideways I5. This control chain is of the conventional block type and is guided at the ends of the guide shell by horizontal guide rolls I9 and 20, the latter being in the form of a chain sprocket. The front guide roll I9 is journaled on a shaft-2| carried by a member 22 which is adjustable longitudinally of the guide shell. A bolt 23 formed on the member 22 extends rearwardly through an opening in a depending lug 24 integral With a guide shell, and nuts 25 and 26 threaded on the bolt 23 respectively engage the opposite sides of the depending lug for adjusting and locking the movable member 22. It will thus be seen kthat when one of the nuts is loosened, the other may be adjusted relative to the bolt to adjust the member 22, and thereafter the 'nuts may be tightened against the lug to lock the member in its adjusted position. By the provision of the adjustable member 22 for the front guide roll I9, the distance apart of the rolls may be varied thereby initially totension the control chain so that it is maintained in proper engageo ment with the guide rolls.

Arranged at the rear end of the guide shell is an intermittent motion control means generally designated 21, enclosed within a casing 28 rigidly secured to the guide shell by bolts 29. The chain sprocket 2li is keyed to a shaft 30 suitably journaled within the teasing, and has formed integral therewith at its .lower end a rotatable ratchet ring 3I of a ratchet-and-pawl device for controlling the direction of rotation of the sprocket. In this construction, a conventional pawl carrier is arranged concentrically within the ratchet ring and carries pawls yieldingly pressed into engagement with internal ratchet teeth formed on the ratchet ring. A shifter annulus 32 is rotatably mounted in the casing and is provided with openings 33 through Which the pawls may move into engagement with the ratchet teeth, and the inner surface of theY annulus is engageable with the pawls for pressing the latter inwardly out of engagement with the ratchet teeth. An operating handle 34 is connected to the shifter annulus for moving the latter into its; diilerent operating positions. Since the detailed structure of the control means 2l forms noY part of the present invention further' description `of the same is herein unnecessary.

Now referring to the improved means for yieldingly drawing the control chain around the guide rolls I9 and 29 and for attaching the control chain to the drill hammer motor, it will be noted that a depending bossy 36 formed on the cylinder 3 of the drill hammer motor projects downwardly within the guide shell between the guideways I5, in the manner shown. A bore 31 extending through the boss parallel to the longitudinal axis of the drill is closed at its rearward end by a plug 38. Reciprocably mounted in the boss-bore 31 is a piston or plunger 39 having a tubular piston rod 40 projecting within a bore 4I in a sleevelike member 42. This member 42 has a portion fitting the forward end of the boss-bore 3l, and the member 42 and the plug 38 are firmly secured to the boss by a bolt 43, the latter extending centrally through the piston and piston rod and an opening in the plug and having threaded thereon at its rear end a tightening nut 44 engaging the plug. The bolt 43 has a squared head litting into a groove in the member 42 so that it is held against rotation, in an obvious manner. Arranged in the boss-bore between the plug and piston and encircling the bolt 43 is a relatively light, flat helical spring 45 for urging the ,piston 39 toward its foremost position thereby to maintain the control chain under a light tension. As shown in Fig. 3, the sleevelike member 42 is slotted longitudinally at 46 along one side and projecting laterally through and movable Within this slot is an arm 4'I integral with the piston rod 40 and one end of the control chain I8 is connected at 48 to this arm while the other end of the control chain is connected at 49 to the member 42.

The throttle valve I0 has passage means for controlling the supply of pressure lluid from the supply connection I3 to the hammer motor and when the hammer motor is running, a port 50 in the throttle valve may connect with a passage 5I so that pressure fluid may be conducted, concurrently with the running of the hammer motor, to the boss-bore 3l at the rear side of the piston 39, the pressure fluid acting on the rear pressure area of the piston to urge the latter forwardly thereby to maintain the control chain under a predetermined maximum tension. When the supply of pressure fluid to the hammer motor is interrupted, and the hammer motor is stopped, the throttle valve may be moved into a position wherein the supply of pressure iiuid to the bossbore is cut on' and a groove 52 on the valve at'that time connects the passage 5I with a vent port 53 so that the boss-bore at the rear side of the piston is connected to exhaust.

In assembling thedrill for operation, the ends of the control chain are first connected at 48 and 49 to the hammer motor cylinder and then the guide roll I9 is moved forwardly by adjusting the nuts 25 and 26 on the bolt 23 until the control chain is tightened, and the piston 39 is moved rearwardly in the boss-bore partially compressing the spring 45, as shown in Fig. 4. It will be noted that the end of the control chain connected at 49 to the sleevelike member 42 will be held in a xed `position relative to the cylinder boss 36 and that the end of the control chain connected at 48 to the piston rod 39 will be continuously pulled tightly around the guide rolls I9, 29, due to the action of the spring 45 against the piston 39. The strength of the spring will be such that the control chain will always be held around the guide rolls under a light tension. When uid under pressure is supplied to the boss-bore 3l to act on the piston 39, the control chain is placed under a maximumtension which produces the most effective feed and, as the drill hammer motor operates, the control chain will be moved around the guide rolls on each jump of the motor, without appreciable loosening of the chain.

When the throttle Valve I0 is open and pressure uid is supplied to the cylinder bore of the hammer motor, the hammer piston 5 is rapidly reciprocated to deliver impact blows to the drill steel and the reciprocatory movements of the hammer piston cause, due to the sudden reversal of the direction of movement of the piston, vibratory or recoil movements of the hammer motor in opposite directions longitudinally thereof as is well understood by those skilled in the art, resulting in alternating tendencies of movement of the hammer motor forwardly and rear- Wardly with respect tothe guide shell. Forward movements of the hammer motor are transmitted to the control chain I8 through the connection 48 and piston 39, and rearward movements of the hammer motor are transmitted to the control chain through the connection 49 and sleevelike member 42. Movement of the control chain in the direction opposite to which it is desired to effect drill feed is checked automaticallyby the ratchet-and-pawl mechanism of the control means 21, the pawls engaging the ratchet teeth to check reverse movement of the vhammer motor and slipping relative to the ratchet teeth to permit free movement of the hammer motor in the feeding direction.

In the modied form of the invention shown in Fig. 5, an automatic pressure-reducing valve, generally designated 55, is arranged between the throttle valve IIJ and the boss-bore 31 for regulating the pressure of the fluid acting on the chain tensioning piston 39. In this construction, the port 50 in the throttle valve is com.- municable with a passage 56, the latter in turn communicating with a passage 51 under the control of a ball valve 58, the passage 51 opening into .the boss-bore 31 at the rear side of the piston 39. A spring 59 yieldingly presses the ball valve 58 against a seat 68 surrounding the opening of pas sage 56 into the valve recess, and the tension of the spring is adjustable by an adjustable follower 6I. When the throttle valve I9 is moved into a position to cut 01T the supply of pressure to the hammer motor, the groove 52 on -the valve con-v` nects the passage 51 with the vent port 53, there-,- by to open the boss-bore 31 to atmosphere. It will thus be seen that by adjusting the spring action on the ball valve the pressure in the boss;-` bore may be regulated at will, thereby to vary the tension on the control chain as desired. By the provision of the pressure reducing valve, the possibility of over-tensioning the control chain may be prevented.

Themode of operation of the modied form of the invention is as follows. As in the embodiment of the invention above described, the ends of the control chain are attached at 48, 49 to the elements 46 and 42, respectively, and the control chain is tightened by the pressure of the uid acting on the piston 39 when the throttle valve IU is adjusted to supply pressure fluid to the drill hammer motor. At this time, pressure fluid can enter the passage 56 through the port 50 and move the ball valve 58 from its seat so that the pressure fluid can enter the passage 51 and be conducted to the boss-bore where Vit acts on the piston S9 to move the member 40 forwardly and increase the tension on the control chain. As soon as the pressure in the boss-bore 31 becomes approximately equal to the line pressure less the pressure of the spring the ball valve 58 is pressed to its seat by the spring 59 and prevents any escape of pressure fluid from the passage 51 to the passage 55. The pressure in the boss-bore 3:1 may be regulated by properly adjusting the tension of the spring 59. When the throttle valve I6 is rotated to a position to shut off supply of pressure to the hammer motor, the connection of the port 56 with the passage 56 to cut oi and the passage 51 is vented to atmosphere through the groove 52 and vent port 53. form of invention is similar to that above described.

In the modified form of the invention shown in Fig. 6, the chain tensioning means is similar to that shown in Fig. 4, except the means for sup- Otherwise this -plying pressure fluid to the boss-bore to effect tensioningof the control chain is omitted and chain tensioning iseiected solely by means of a coil spring. In this construction, a spring 63 of substantially greater strength than the spring 45 is interposed between the plug 38 and a ange 64 formed on a sleevelike member 65 with which one end of the control chain has connection at 66. The other end of the control chain is connected at 6.1 to a sleevelike member 68 similar to the member 42 above described, and' similarly held in position by a bolt 43. In this instance, the bolt 43 has its squared head tting into a square .recess in the member 68, so that the bolt is held against rotation. The sleevelike member 65 projects within the bore in the sleevelike member 68 and has an itegral arm 69 projecting laterally through and movable within a longitudinal slot 10 in the member 68, the control chain being connected at 66 to the arm 69. The spring 63 acting between the plug 38 and the flange 64 yieldingly urges the member 65 forwardly with respect to the member 68 so that the ends of the control chain will be continuously pulled tightly around the guide rolls and the strength of the spring 63 will be such that the control chain will always be held around the guide rolls at a tension which provides the most effective feed. This form of the invention is otherwise similar to that above described and operates in a similar manner with the exception that when the drill hammer motor is stopped the tension on the control chain' is not reduced or relieved.

As a result of this invention it will be noted that an improved yieldable tensioning device for the control .chain of the vibration controlled feeding means of a hammer rock drill is provided. It will further be noted that 'improvedv means have been provided for automatically increasing the tension of the control chain during operation of the `drill hammer motor to obtain the maximum effectiveness of drilll feed and that the tension on the control chain is automatically decreased and the strain on the associated parts is automatically reduced when the hammer motor is shut down. It will further be evident that the improved tensioning device is not only compact and rugged in construction, but is simple in design and composed of parts which may be inexpensively constructed and easily replaced. Other uses and advantages of the improved chain tensioning device will be readily apparent to those skilled inthe art. Y

While there are in this application specically described two forms and a .modification which the invention may assume inpractice, it will be understood that these forms and modification of the same are shown for purposes of illustration and that the invention may be further modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure'by Letters Patent is:

l. In a rock drill, the combination of a guide providing a guideway, a pressure fluid actuated drill motor of the reciprocating piston type slidably mounted on the guldeway of said guide, means controlled by vibrations set up within said motor for effecting feed of the latter along said guideway, said motor feed effecting means comprising a flexible control element having parallel strands extending longitudinally of said guide, rotatable members at the ends of saidf motor guide for guiding said flexible control element, means for rigidly attaching one end of said flexible control element to said drill motor, pressure fluid actuated means carried by said drill motor and attached to the other end of said flexible control element for increasing the tension on the latter, and means for controlling the supply of pressure fluid tosaid pressure fluid actuated means.

2. In a rock drill, the combination of a guide providing a guideway, a pressure fluid actuated drill motor of the reciprocating piston type slidably mounted on the guideway of said guide, means controlled by vibrations set up within said motor for .effecting feed of the latter along said guideway,said motor feed effecting means comprising a flexible control element having parallel strands extending longitudinally of said guide, rotatable members at the ends of said motor guide for guiding said flexible control element, means attached to the ends of said control element for yieldingly drawing the latter around said rotatable members and securing the same to said motor, pressure fluid actuated means carried by said drill motor and attached to said control element for increasingthe tension on the latter on supply of pressure fluid thereto, means for supplying pressure fluid to said pressure fluid actuated mean-s simultaneously with the supply of pressure fluid to said drill motor, and means for venting pressure fluid from said pressure fluid actuated means simultaneously with the cutting off of pressure fluid supply to said drill motor.

3. In a rock drill, the combination of a guide providing a guideway, a pressure fluid actuated drill motor of the reciprocating piston type slidably mounted on the guideway of said guide, means controlled by vibrations set up within said motor for effecting feed of the latter along said guideway, said motor feed effecting means comprising a flexible control element having parallel strands extending longitudinally of `said guide, rotatable members at the ends of said motor guide for guiding said flexible control element, means attached to the ends of said control element for yieldingly drawing the latter around said rotatable members and securing the same to said motor, pressure vfluid actuated means carried by said drill motor and attached to said control element for increasing the tension on the latter on supply of pressure fluid thereto, and means including a manually controlled valve for controlling the supply of pressure fluid to vand the venting of pressure fluid from said pressure fluid actuated means.

4. In a rock drill, the combination of a guide providing a guideway, a pressure fluid actuated drill motor of the reciprocating piston type slidably mounted on the guideway of Said guide, means controlled by the longitudinal vibrations set up within said motor for effecting feed of the latter along said guideway, said motor feed effecting means comprising a control chain having parallel strands extending longitudinally of said guide, rotatable members at the ends of said guide for guiding said control chain, and mea'ns for drawing said control chain around said rotatable members and for connecting the ends of said feed chain to said drill motor, said last mentioned means comprising a portion formed on said drill motor and projecting between the parallel strands of said feed chain, means for rigidly attaching one end of said control chain to said projecting portion, a bore formed in said projecting portion, a piston reciprocable in said bore and having a transversely extending portion for connecting to the other end of said control chain, a spring arranged in said bore and pressing against said' piston for placing a tension on said control.' chain, means for supplying pressure fluid to said bore to act upon said piston and effect an increase in the tension on said control chain, means for venting pressure fluid from said bore, and manually controlled means for controlling said pressure fluid supplying and venting means.

5. A rock drill comprising, in combination, a drill hammer motor of the reciprocatory hammer piston type in which longitudinal vibrations in opposite directions are set up during running of the motor, a guideway along which said motor is guided, means controlled by the vibratory movements of said hammer motor for controlling the direction of movement of said motor along said guideway including a flexible controlling element and guide rolls at the opposite ends of said guideway for guiding said flexible element, and means for automatically tensioning said flexible element during running of the motor and for automatically reducing the tension thereof when the motor is stopped.

6. A rock drill comprising, in combination, a drill hammer motor of the reciprocatory hammer iston type in which longitudinal vibrations in opposite directions are set up during running of the motor, a guideway along which said motor is guided, means controlled by the vibratory movements of said hammer motor for controlling the direction of movement of said motor along said guideway including a flexible control element and guide rolls at the opposite ends of said guideway for guiding said flexible element, means for automatically tensioning said flexible element during running of the motor and for automatically reducing the tension thereof when the motor is stopped, said tensioning means comprising a fluid cylinder containing a reciprocable piston, means for connecting said piston to said control element, and means for supplying pressure fluid to said cylinder.

'7. A rock drill comprising, in combination, a fluid actuated drill hammer motor of the reciprocatory hammer piston type in which longitudinal vibrations in opposite directions are set up during running of the motor, said motor having a throttle valve for controlling the flow of pressure fluid thereto, a guideway along which said motor is guided, means controlled by the vibratory movements of said hammer motor for controlling the direction of movement of said motor along said guideway including a flexible control element and guide rolls at the opposite ends of said guideway for guiding said flexible element, and means for automatically tensioning said flexible element during running of the motor and for automatically reducing the tension thereof when the motor is stopped, said tensioning means comprising a fluid cylinder containing a reciprocable piston, means for connecting said piston to said control element, and means controlled by said throttle valve for supplying pressure fluid to said fluid cylinder.

5 3. A rock drill comprising, in combination, a drill hammer motor of the reciprocatory hammer piston type in which longitudinal vibrations in opposite directions are set up during running of the motor, a guideway along which said motor is guided, means controlled by the vibratory movements of said motor for effecting step by step feed of said motor along said guideway, said feed effecting means including a flexible controlling element and a rotatable controlling element cooperating therewith, and means for automatically tensioning said flexible controlling element during running of the motor and for automatically reducing the tension thereof when the motor is stopped.

9. A rock drill comprising, in combination, a

, drill hammer motor of the reciprocating hammer piston type in which longitudinal Vibrations in opposite directions are set up during running of the motor, a guideWay along which said motor is guided, means controlled by the Vibratory movements of said motor for effecting step by step feed of said motor along said guideway, said feed effecting means including a flexible controlling element and a rotatable controlling element cooperating therewith, and means actuated by pressure fluid for automatically tensioning said flexible controlling element during running of the motor and for automatically reducing the tension thereof when the motor is stopped.

10. A rock drill comprising, in combination, a drill hammer motor of the reciprocatory hammer piston type in which longitudinal vibrations in opposite directions are set up during running of the motor, a guideway along which said motor is guided, means controlled by the Vibratory movements of said motor for eecting step by step feed of said motor along said guideway, said feed effecting means including a flexible controlling element and a rotatable controlling element cooperating therewith, and means actuated from the same power source as said motor for automatically tensioning said flexible controlling element during running of the motor and for automatically reducing the tension thereof when the motor is stopped.

11. A rock drill comprising, in combination, a

' drill hammer motor of the reciprocating hammer piston type in which longitudinal vibrations in opposite directions are set up during running of the motor, a guideway along which said motor is guided, means controlled by the vibratory movements of said motor for effecting step by step feed of said motor along said guideway, said feed effecting means including a flexible controlling element operatively connected to said motor, rotatable guides mounted on said guideway for guiding said flexible controlling element, said flexible controlling element having circulatory movement relative to said guideway and said guides during feeding of said motor, means for yieldably maintaining said flexible controllingl element under tension with respect to said guides during the drilling operation, and means associated with one of said guides for controlling the direction of rotation thereof.

12. A rock drill comprising, in combination, a drill steel actuator, a guideway along which said drill steel actuator is guided for movement toward the work, means for effecting feed of said drill steel actuator along said guideway including a flexible feeding element and a rotatable feeding element cooperating therewith, and means energized independently of the forces set up due to the putting into operation of said drill steel actuator for automatically exertingupon said flexible f element during operation of said drill steel actution of said drill steel actuator for'automatically exerting upon said flexible element during opera- 1 tion of said drill steel actuator a tensioning force which is discontinued when operation of the drill steel actuator ceases.

JOHN C. CURTIS.

CERTIFICATE oT CCRRRCTICN. Patent No. 2,513,59LI. May II, 191g.

JOHN C. CURTIS.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5, first column, line 68, for "to" read -is; and second column, line l?, for itegral read --integral; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of October, A. D. 1911.5.

\ Henry Van Arsdale (Seal) Acting Commissioner of Patents. 

